The shortest 'legal' sentence I can come up with is 82 Characters
"Why did Microsoft Entertainment Pack have a sticker announcing that it had Tetris?"
The had... had... is doing the heavy lifting for omitting the 'did' - but it's perfectly comprehensible.
More to the point, 'English' doesn't have a Universal agreed dialect, pronunciation, or spelling. You'd lose your mind trying to square the circle of Hiberno English - the language of Joyce, Beckett, Keane, Wilde, Yeats et al - based on your notions of 'proper' English.
How about
> Why did Microsoft Entertainment Pack announce that it had Tetris
> The shortest 'legal' sentence I can come up with is 82 Characters
You can put the mangled headline into actual English by shortening it:
Why Microsoft Entertainment Pack had a sticker announcing that it had Tetris